and follow the download instructions for the mingw-get-inst installer. This is an easy to use installer for installing both MinGW and MSYS. Make sure when you run the installer that you select to install g++, MSYS and the MSYS Dev Kit.

Set your PATH. We recommend doing this by creating a file .profile in your home directory (by default c:/MinGW/msys/1.0/home/<username>). The contents of your .profile should be something like this:

Modify the above according to where you installed Git and Python. The Haskell platform installer should have already done the work needed to make GHC available on the path.

Launch the shell by starting the 'MinGW Shell' which should be in your start menu.

You should now have a working environment for getting the source for GHC and building it!

Disable realtime virus-scanning for your build

Realtime virus scanners are prone to causing weird build failures, typically "permission denied" errors that go away when the build is restarted. The best way to avoid these problems is to exclude the directory containing your GHC build from realtime virus scanning, if your scanner supports excluding particular directories. You probably also want to exclude directories in which temporary files are stored, which by default is C:/Users/<user>/Local Settings/Temp on Windows Vista and later, C:/Documents and Settings/<user>/Local Settings/Temp on Windows XP and older, or C:/Temp.

Building documentation on Windows

Building GHC's documentation is optional, but in order to build it in Windows you must currently use Cygwin (there isn't a working DocBook toolchain on MSYS as far as we know).

In the Cygwin installer, just install the complete Doc category. You may have to help configure a little bit: Set the environment variables XmllintCmd and XsltprocCmd to the paths of the Cygwin executables xmllint and xsltproc, respectively, and set fp_cv_dir_docbook_xsl to the path of the directory where the XSL stylesheets are installed, e.g. c:/cygwin/usr/share/docbook-xsl.

If you want to build HTML Help, you have to install the ​HTML Help SDK, tool, and make sure that hhc is in your PATH.